Implement list.reverse.

runtime/list.go

@@ -304,6 +304,21 @@ func listRepr(f *Frame, o *Object) (*Object, *BaseException) {
 	return NewStr(fmt.Sprintf("[%s]", repr)).ToObject(), nil
 }
 
+func listReverse(f *Frame, args Args, _ KWArgs) (*Object, *BaseException) {
+	if raised := checkMethodArgs(f, "reverse", args, ListType); raised != nil {
+		return nil, raised
+	}
+	l := toListUnsafe(args[0])
+	l.mutex.Lock()
+	halfLen := len(l.elems) / 2
+	for i := 0; i < halfLen; i++ {
+		j := len(l.elems) - i - 1
+		l.elems[i], l.elems[j] = l.elems[j], l.elems[i]
+	}
+	l.mutex.Unlock()
+	return None, nil
+}
+
 func listSetItem(f *Frame, o, key, value *Object) *BaseException {
 	l := toListUnsafe(o)
 	if key.typ.slots.Int != nil {
@@ -322,6 +337,7 @@ func listSetItem(f *Frame, o, key, value *Object) *BaseException {
 func initListType(dict map[string]*Object) {
 	dict["append"] = newBuiltinFunction("append", listAppend).ToObject()
 	dict["insert"] = newBuiltinFunction("insert", listInsert).ToObject()
+	dict["reverse"] = newBuiltinFunction("reverse", listReverse).ToObject()
 	ListType.slots.Add = &binaryOpSlot{listAdd}
 	ListType.slots.Contains = &binaryOpSlot{listContains}
 	ListType.slots.Eq = &binaryOpSlot{listEq}

runtime/list_test.go

@@ -246,6 +246,27 @@ func TestListNew(t *testing.T) {
 	}
 }
 
+func TestListReverse(t *testing.T) {
+	reverse := mustNotRaise(GetAttr(newFrame(nil), ListType.ToObject(), NewStr("reverse"), nil))
+	fun := wrapFuncForTest(func(f *Frame, o *Object, args ...*Object) (*Object, *BaseException) {
+		_, raised := reverse.Call(f, append(Args{o}, args...), nil)
+		if raised != nil {
+			return nil, raised
+		}
+		return o, nil
+	})
+	cases := []invokeTestCase{
+		{args: wrapArgs(NewList()), want: NewList().ToObject()},
+		{args: wrapArgs(newTestList(1, 2, 3)), want: newTestList(3, 2, 1).ToObject()},
+		{args: wrapArgs(NewList(), 123), wantExc: mustCreateException(TypeErrorType, "'reverse' of 'list' requires 1 arguments")},
+	}
+	for _, cas := range cases {
+		if err := runInvokeTestCase(fun, &cas); err != "" {
+			t.Error(err)
+		}
+	}
+}
+
 func TestListStrRepr(t *testing.T) {
 	recursiveList := newTestList("foo").ToObject()
 	listAppend(newFrame(nil), []*Object{recursiveList, recursiveList}, nil)